The present invention relates to a butterfly valve element mounted on a shaft and rotatable to regulate flow of a fluid in a flow passage, and more particularly, the present invention relates to a butterfly valve element used to regulate air in an air inlet conduit of a throttle body or carburetor of an internal combustion engine.
A conventional butterfly valve includes a disc-shaped plate positioned in a duct, conduit, or throat, for rotation about a transverse axis defined by a shaft. Rotation of the plate in the passage increases or decreases the amount of restriction to fluid flow and thereby controls fluid flow through the duct, conduit or throat. Some examples of butterfly valves are disclosed by U.S. Pat. Nos. 1,857,477 issued to Ritter; U.S. Pat. No. 1,841,695 issued to Anderson; U.S. Pat. No. 2,105,343 issued to Briggs; U.S. Pat. No. 3,176,704 issued to De Palma; U.S. Pat. No. 4,420,438 issued to Goosen; U.S. Pat. No. 4,996,769 issued to Bongert; U.S. Pat. No. 6,371,068 B2 issued to Taylor; and U.S. Pat. No. 6,439,540 B1 issued to Tse and by U.S. Patent Application Publication Nos. 2007/0102661 A1 of Isogai et al. and 2005/0172924 A1 of Simon.
U.S. Pat. No. 5,342,555 issued to Edmonston and U.S. Patent Application Publication No. 2005/0172924 A1 of Simon disclose devices that are used to straighten air flow upstream and/or downstream of air-regulators within carburetors and throttle bodies. For example, both references disclose a conventional carburetor having an air inlet conduit and a slide-type air regulator typically used on motorcycles or all-terrain vehicles (ATVs), and Simon discloses a fuel-injector style throttle body having an air conduit and butterfly valve-type air regulator. The air flow straightening devices are mounted in a stationary position on either end of the air conduit for reducing air turbulence within the carburetor or throttle body directly ahead of, or behind, the air regulator. These devices are used to straighten and accelerate the air flow through the carburetor or throttle body for purposes of increasing response, power and torque.
Although the valve assemblies disclosed in the above referenced patents and application publications may be satisfactory for their intended purpose, there is a need for a butterfly valve that reduces air turbulence and that straightens and accelerates air flow across a butterfly valve element. The butterfly valve can be used in a throttle body for providing increased air speed and greater torque. In addition, the butterfly element should be easy to install within a throttle body, including retrofits of existing throttle bodies, and should require only a minimum of skill and labor to install.